Centralized traffic control system for railroads



F. T. PAscoE 3,015,722

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Frank 7? Pascoe BY (/l ru/' H125 ATTORNE' Y United States arent 3,015,722 CENTRALIZED TRAFFIC CONTROL SYSTEM FOR RAILRADS Frank T. Pascoe, Scott Township, Allegheny County, Pa.,

assigior to Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania Filed Feb. 4, 1959, Ser. No. 791,135 43 Claims. (Cl. 246-5) My invention relates to centralized traffic control systems for railroads, and particularly to control systems of this type in which a large number of railway signals and track switches at separate field stations are controlled from a control office over a single line circuit, `and in which the same line circuit is employed to indicate at the control office the positions assumed by the switches and signals at the various field stations. More particularly, my invention relates to means at the control office for selecting each individual field station and establishing the commands normally referred to as controls, to be transmitted to each selected station.

The means heretofore usually employed for tthe selection of field stations to which controls are to be transmitted, and for establishing the contro-ls to be transmitted to the selected stations, consists of a group of control levers and push buttons provided for each field station and mounted on a control machine which includes a miniature track diagram of the track layout of the railway territory to be controlled. For the purpose of establishing correspondence between each group of control levers and push buttons and the corresponding field station on the miniature track diagram, the diagram is designed so that each respective field station appears on the diagram in a position relative to its respective group of control devices. The spacing of the field stations on the track diagram and the size of the control machine are, therefore, controlled by the space on the machine required for mounting the control devices. Since it is desirable that all the control devices be in convenient reach of an operator seated at the control machine, it is apparent that the railway territory that can be conveniently controlled from la single conventional control machine is limited, due to the space required for the control levers and push buttons.

In order to reduce the size of the control machine required for control of a section of railway territory, or in order to increase the size of the territory that may be conveniently controlled from a control machine, it is proposed to remove the control levers and other contiol devices from the control machine, and to provide a single group o-f control devices on a control panel or keyboard for selecting the individual field stations and establishing the controls to be transmitted to each selected station. By the removal of the control devices from the control machine, the miniature track diagram thereonA may be further miniaturized and vertically tiered to provide a reproduction of a section of railroad territory of a maximum size. The size of the railroad territory that may be thus represented is limited only by the operato-rs ability to readily read station and other designations appearing on the diagram.

ln the above described type of centralized traiiic control systems, requiring only a single line circuit between the control oice and field locations for transmission of both controls and indications, a selective communication system of the code type is employed for the remote control system. This type of communication system is well known in Ithe art and may, forV example, be the type of system shown in Letters Patent of the United States, No. 2,698,425, issued December 28, 1954, to Alfred B. Miller, for a Remote Control System, which ice system is illustrated and described in a publication of the Union Switch & Signal Division of Westinghouse Air Brake Company, of Swissvale, Pa.; entitled Manual No. 5,14, revised in September 1956.

In the type of communication system as outlined above, it is recognized that a group of control codes can be transmitted from the control office to `only one field station at a time, that only one group of indication codes can be transmitted from a field station to the control office at any one time, and that a group of control codes cannot be transmitted to a field station when another field station is transmitting a gro-up of indication codes. It is thus apparent that, because control codes are being transmitted to a field station or indication codes are being received yfrom a field station, there may be a time delay between the initiation of a group of control codes for another field station and the transmission of this group of codes to this other eld station.

When a single group of control devices mounted on a control panel or keyboard is employed for initiating control codes to be transmitted to the various field stations, it is desirable, to avoid time delays, that the control codes for one field station may be initiated and that the panel may be immediately available for the initiation of control codes for another field station. To accomplish this availability of the control panel, and because of the above described time delay that can occur between the initiation of a group of control codes and the transmission of these codes to their respective field station, it is necessary to provide a memory system for the control codes initiated for transmission to" each field station. In the conventional type of control machine, Where a group of control levers is provided for each field station, the control devices themselves provide t-he memory system because the levers may be manipulated to various positions and allowed to remain in said positions until the control codes established by the positions of the control devices are transmitted to the respective field location. However, in employing a keyboard or control panel of the type described, it is readily recognized that the control devices on the panel are not always available to provide the necessary memory system since the control devices on the panel are employed, at various times, to establish control codes for all the field stations in the controlled railroad territory. A group of memory relays for each field station is, therefore, required in the control office for storing the control codes to be transmitted to each respective field station. When as in the usual centralized trafc control system, the field stations are relatively numerous, and when the number of functions at some field stations is relatively high, the number of memory relays required at the control oiice may be economically unjustifiable, thereby nullifying any economic advantage obtained by the reduction in size of the track diagram and the control machine, or the increase in size of the railroad territory that may be conveniently controlled by a single operator at a single control panel. Y

It is accordingly the principal object of my invention to eliminate the necessity for the memory relays in systems of the class described, wherein a single group lof control devices at a control office is employed for controlling a group of functions at each of a plurality of field locations. Y

lt is another object of my invention tovprovidie new and novel means for establishing command or control codes to be transmitted from a control oliice to the various eld stations in a centralized traffic control system for railroads. y

Other objects and characteristic features of my invention will become apparent as the description proceeds.

In accomplishing the foregoing objects of my invention, I utilize the indicatingrelays, normally provided at the control office for indicating the condition of switches and signals at the various eld locations, as control storage or memory relays, in addition to their usual use as indication relays. The manner in which this is done will become apparent hereinafter as the description proceeds. v

One form of apparatus embodying my invention will now be described and the novel features thereof will then be pointed out in claims.- f

In the drawings, FIG. la is a diagrammatic view showing an alluminated track diagram of a track layout of a typical siding location in centralized traffic controlled railroad territory. For purposes of simplification of the description, only two field stations, one at each end of the siding are illustrated. FIG. lb shows the circuit arrangement for the illumination of the indication lamps shown only diagrammatically in FIG. la but which will in actual practice be mounted in the diagram of the track layout illustrated in FIG. la. The association between the filaments of a various lamps shown in FIG. lb and their respective location in the track diagram shown in FIG. la is believed readily apparent but will be described in more detail as the description proceeds. It is also lbelieved readily apparent that the illustrated track diagram is so located in the control office as to be in convenient view of the dispatcher or operator manipulating various controls to be transmitted to the field locations shown.

FIG. 2 of the drawings shows two groups of push buttons which arel located on a control panel or keyboard and are employed by the operator to select each field station, or location to which control codes are to be transmitted. FIGS. 3a, 3b and 3c show the function control push buttons and a series of relays which repeat the manipulations of the push buttons. These push buttons are also located on the control panel along with the station or location selection push buttons.

FIG. 4a shows the manner in which contacts of indication relays in the control office are employed for transmission of the function control codes to the field locations. The apparatus shown on the left-hand side of the arrows is located in the control office and the apparatus shown on the right-hand side of the arrows is located at the field locations, the relays shown on the right-hand side comprising the usual final stick relays at the field locations. FIGS. 4b, 4c and 4d show several relays ernployed in the code control system used for the illustration of my new invention and will be further described later on inthe specification.

FIGS. 5, 6 and 7 show the manner in which the indication relays are manipulated to store control codes, and also the manner in which these relays are employed to repeat the positions of various relays at the field locations to indicate at the office the condition of the lield apparatus. Similarly as in FIG. 4a, the apparatus shown on the left-hand side of the arrows in FIGS, 5, 6 and 7 is located at the controlofiice, and the apparatus shown on the right-hand side of the arrows is located at the field locations.

It is expedient to point out at this time that energy for operation of the apparatus shown in the drawings is furnished by suitable sources of direct current at each location, such as a battery of proper voltage and current. For sake of simplicity these sources of current are not shown in the drawings, but the positive and negative terminals of each source are identified in each instance by the reference characters Band N, respectively.

It isv alsol expedient to point out at this time that the form of apparatus embodying my invention and described herein is illustrated as employing a communication system of the type shown in aforementioned Letters Patent of the United States, No. 2,698,425, issued to Alfred B. Miller. However, it is to be understood that any type of communication system may be employed in conjunctionvvyithl the apparatus of my invention, and it is not inincidence between the two digits of the location designation numerals and the last two digits of the iield station code numeralsis indicative of nothing, but the similar numerals were chosen to assist in avoiding confusion in the description of the operation of the apparatus of my invention. The code control communication system of the aforesaid Miller patent is a 35 station systeml or capable of transmitting controls and indications to andV from 35 eld stations; but, by employing additional sets of the communication system equipment, the number of field stations associated with a single control panel is virtually unlimited. However, for purposes of this description it is assumed that field station 235 at location 3S and field station 236 at location 36 are both controlled by the same code control communication system.

The track switch at location 35 in FIG. la is designated .3S-1W and has normal and reverse indication lamps designated NKE and RKI-E, respectively. The signal at said location for governing train movements to the right into the siding area is designated 35S-2R and has two indication lamps designated AKE and BKE. The signal for governing train movements to the left out of the main track in the siding area is designated SS-ZLA, and the signal for governing train movements to the left out of the siding track is designated 35S-2LH Each of these signals also has two indication lamps, each pair also being designated AKE and BKE; however, by the location of the said signal indication lamps on the track diagram it is readily recognized with which signal each pair of lamps is associated.

The track switch at location 36 in FIG. la is designated 'S6-1W and also has normal and reverse indication lamps designated NKE and RKE, respectively. The sigv nais at this location are designated 36-2RA and Bd-ZRB, and 36-2L, controlling train movements to the right or left as indicated by the letter R or L included in their designations. Each of these signals also has a pair of indication lamps each designated AKE and BKE. 'The indications displayed by the signal indication lamps will be described later on in this description.

The filaments of the above described indication lamps are shown in FIG. lb and are designated by the designation of the signal or switch with which they are associated sufiixed by the designation of the respective indication lamp. For example, the filament of the AKE indication lamp for signal 35-2LA (FIG. la) is designated 35-2LAAKE and the tilament'of the NKE indication lamp for switch :d-1W (FIG. la) is designated 36- IWNKE. The association between the filaments of the lamps shown in FIG. lb and the lamps designated on the track diagram in FIG. la is, therefore, readily apparent. The filaments of the lamps are normally deenergized and therefore the track diagram is normally dark. The circuits for energization of the lamp filaments will'be described hereinafter in the description. Y

There is also shown in FIG. lb, a code transmitter re lay designated by the reference character CTR. As is obvious the terminals of this relay are connected to terminals B and N ofthe battery and the relay is, therefore, constantly operating to periodically open and close its front contacts a. These relays and their operation are well known in the art and any type of such relay may be employed. Terminal B of the battery is connected to the movable portion of contact a of relay CTR and. a form of coded energy designated CB appears at the front point vof contact a of the relay. This coded energy is employed to provide additional indications by intermittently flashing the indication lamps AKE, BKE, NKE and RKE under conditions that will hereinafter be described. FIG. 2 of the drawings shows the field station selection push buttons which are located on the keyboard or control panel and the circuit arrangement controlled by the push buttons. As previously set forth, two groups of push buttons are provided. The rst group comprises the tens digit push buttons which establish the tens digit of a ield location designation, such for example, as the digit 3 in the numeral 35 employed for designation of field location 35 illustrated in FIG. la; or in the designation for a field location 21, not shown in the drawings, the digit 2 in the numeral 21 employed for the designation of such a field location. The second group of push buttons comprises the unit digit push buttons which establish the unit digits of field location designations, such as the digit 5 or l, respectively, in the examples set forth above. This group of push buttons are designated OPB through 9PB for the unit digits 0 through 9, respectively.

For purposes of illustration of my invention only three tens digit push buttons are shown in FIG. 2 and, by employing these in conjunction with the ten unit digit push buttons, a total of 39 field stations or locations may be selected (omitting the use of tlPB push button alone for selecting a held station). These three tens digit push buttons are designated lDPB, ZDPB and SDPB for selecting the tens digits l, 2 and 3, respectively, as is obvious. It is apparent that, by providing 9 tens digit push buttons for use in conjunction with the ten unit digit push buttons provide, a total of 99 field stations could be selected (again omitting the use of push button GPB alone for selecting a field station). It is also apparent that by providing a third or hundreds digit group of push buttons the arrangement shown could be expanded to control a total of 999 held locations (omitting UPB as before). It should be pointed out that in the arrangement shown in FIG. 2 one of the unit digit push buttons IPB through 9PB only would be operated to select a field station having the location designations 1 through 9, respectively. No tens digit push button would be operated to select these field locations.

Each of the groups of station selection push buttons IDPB through SDPB and 013B through 9PB are of the stick type and are interlocked with each other. That is to say, a push button which has been depressed will remain or stick in the depressed position until another push button in the same group is depressed or until a concellation winding or coil, to be described later, is energized. The interlocking feature of the push buttons thus permits only one push button in a group to be depressed at any one time. Such interlocked types of push buttons are well known in the art and the interlocking feature of the push buttons forms no part of my present invention.

Each of the tens digit push buttons IDPB through 3DPB is shown in the conventional manner as provided with a movable contact member normally closed against a front contact point and having a normally open or back contact point. Each of the unit digit push buttons 0PB through 9PB is shown provided with a series of movable contact members each having only a normally open or back contact point. The arrow heads on the extensions of the push buttons indicate that the buttons must be depressed to close their back contact points or to open their front contact points.

There is also shown in FIG.V 2 a cancellation push button designated by the reference character CPB. This push but-ton is of the spring return type as shown in the conventional manner by the letter S on the extension of the push button. The button is provided with a movable contact member having a normally open or back contact point. When the push button is depressed the movable contact member closes against the back contact point, as indicated by the arrow head on the extension of the push button, and when the button is released the button is returned to its normal position by the aforesaid spring return action, thereby again opening the aforesaid contact. The utilization of this cancellation button will be described hereinafter. v

A tens digit cancellation coil or winding designated by the reference character DCC and a unit cancellation coil or winding designated by the reference character UCC are also shown in FIG. 2. These windings or coils, sometimes referred to as knockdown coils, control the cancellation of a storage in each respective group of location selection push buttons, which storages are represented by the depressed condition of a push button in each group of push buttons. In other words, each respective cancellation coil, when energized, releases a depressed push button in the respective push button group to permit it to return to its undepressed or normal position. Interlocking types of push buttons provided with cancellation windings or coils are also well known in the art.

A plurality of keyboard or control panel terminals are shown in FIG. 2 by a plurality of circles each enclosing a terminal designation comprising the letter A followed by a numeral, as readily appears. The terminals A1 through A39, if 39 eld locations are to be selected at various times, are each connected to a location selection or control relay similar to relays SSLC and 36LC shown in PIG. 2. However, for the purpose of simplication, since only the -two field locations 35 and 36 are employed in the description of my invention, only the localtion selection relays for these field locations 35 and 36 are shown. These relays are designated 35LC and 36LC for said locations 35 and 36, respectively. One terminal of the winding of relay 35LC is connected to terminal A35 of the control panel, and one terminal of the winding of relay 36L C is connected to terminal A36 of the control panel. The other terminals of the windings of the relays are connected to terminal N of the battery.

Relays SSLC and 36LC are telephone type relays each having a plurality of front and back contact points, open and closed, respectively, when the winding of the relay is deenergized, and closed and open, respectively, when the winding of the relay is energized. Some of the contacts on these relays are dependent contacts so arranged as to constitute so-called make-before-break or continuity contacts. This type of relay is well known infthey art and any such relay having a sufficient number of contacts may be employed for the location selection relays. The make-before-break contacts on the relays are shown with a wiper portion on the end ofthe movable members o-f the contacts as is apparent from the drawings (see for example FIG. 5). The manner in which additional location selection relays may be 'connected to the control panel for the selection of additional field locations is obvious from the above-description and lby reference to FIG. 2 o-f the drawings. The operation of the apparatus for energizing one of the location selection relays 35LC or 36LC will be discussed below.

Control panel or keyboard terminal A111 shown in FIG. 2 is a cancellation control terminal and is utilizedl in a manner to be hereinafter described.

It is believed expedient, at this time, to describe 4the manner in which relays 35LC and 36LC are energized to select their respective field locations. Relay 35LC has a pickup circuit which extends from terminal B of the battery in FIG. 2 over the front point of contact a of push button 1DPBthe front point of contact a of push button ZDPB, the back point of contact a of push button SDPB, thence to the group of unit digit push buttons and over back contact d of push button SPB to terminal A35, and from terminal A35 through the winding of relay 35LC to terminal N of the battery. Relay 35LC has a pickup circuit extending from terminal B of the battery over the front point of Contact a of lDPB, the front point of contact a of ZDPB, the back point of contact a of 3DPB, thence to back contact d of unit digit push ybutton 6PB, terminal A36, and through the winding of relay 36LC to terminal N of the battery. It is thus obvious that when it is desired to energize relay SSLC for selecting eld location 35, the operator depresses push buttons SDPB and SPB on the control panel. These push buttons, being of the stick type, the described circuit is completed to energize relay 35LC and the relay will pick up and remain up as long as the said push buttons remain depressed. Similarly, when it is desired to energize relay 36LC for selecting iield location 36, the operator depresses push `buttons SDPB and PB on the control panel, and relay 36LC is energized over its described pickup circuit and picks up and remains up as long as its said selection push buttons remain depressed. It is to be noted 4that relays 35LC and 36LC cannot be energized simultaneously because push buttons SPB and 6PB cannot be depressed at the same time due to the previously described inter-locking feature of each group of push buttons. As previously stated the manner of energization of other station selection relays that can be provided is apparent from this description of the control of relays 35LC and 36LC. The circuits controlled by relays 351C and 36LC will be described hereinafter.

lf an incorrect location selection relay is inadvertently energized by the operator depressing an incorrect push 'button or buttons, a cancellation may be made by depressing the cancellation `button CPB. The depressing of button CPB closes an energizing circuit for cancellation or knockdown coils DCC and UCC which may be traced from terminal B of the battery over back contact a of CPB in its depressed position and through the coils DCC and UCC in multiple to terminal N of the battery. As previously described, the energization of the cancellation coils permits the depressed push buttons to return to their undepressed position and the field location selection storages on the control panel are cancelled. As will be hereinafter described, automatic cancellation of location selection storages can be accomplished by connecting terminal B of the battery to terminal A111 of the panel. The cancellation circuit from terminal A111 to the cancellation coils is obvious and no detailed description thereof is necessary.

Referring now to FIG. 3a, there is shown a normal switch control push button designate-d lNPB, a normal :repeater relay lNP'wliich is energized by the actuation 'of the normal switch control push button, a reverse switch control push Vbutton IRPE, and a reverse repeater relay ERP which is energized bythe actuation of the reverse switch control push button. The push buttons INPB Vand lRPB are spring return push buttons mounted on the control panel, each having a normally open back contact, and employed for initiating controls for directing a iirst switch at a iield location to normal and reverse positions, respectively. These push buttons are identical in operation to cancellation push button CPB previously described and no further'description of their operation is considered necessary. Relays lNP and IRP are conventional telephone type relays, similar to relays 35LC and 36LC previously described, and no further description of these relays is considered 'necessary except to point out that no make-before-break contacts are provided on these relays.

Terminals A100 and A101 shown in FIG. 3a are terminals on the control panel similar to the terminals shown in FIG, 2, previously described. Terminals Blilt, B101 and 'B162 are multiple connection terminals to which circuits for contacts of all field location selection relays are connected. Because, in this illustrated embodiment of my invention, only two location selection relays are necessary, connection to contacts of these two relays only are shown. However, it should be pointed out that, if additional eld locations are to be selected from the control panel, an additional connection is made from each of the multiple connection terminals to a contact of each additional location selection relay employed.v

Only two switch control push buttons lNPB and lRPB are required on the control panel in the embodiment of my invention illustrated, because there is only one switch at each of the field locations 35 and 36. However, in actual practice the number of switch control buttons which will be required on the control panel will depend on the number of switches at the location having the greatest number of switches, two such buttons being required for each switch at that location. Each of these push buttons wouid also have associated therewith a relay similar to relays NP or lRP (see FIG. 3u) for repeating the switch control push buttons. It is thus apparent that the control panel is so designed as to control all of the functions to be controlled at all of the field locations in a section of railroad territory. During the initiation of the controls for the ield location where a less than the maximum number of functions are to be controlled, the extra control push buttons would not perform any function but would be merely in excess of the number required for control of those locations.

Returning to FIG. 3a, relay lNP has a pickup circuit which extends from terminal B of the battery over the back point of Contact a of push button INPB, terminal Alii, the winding of the relay, multiple connection terminal Bildt), and thence over a multiple circuit comprising two branches, the first branch extending from terminal B over iront contact a of location selection relay LC, previously described, and the front point of contact b of switch indication relay SS-lRWK, to be described, to terminal N of the battery; and the second branch extending from terminal B lliii) over front contact a of location selection relay 36LC, previously described, and over the front point or contact b of switch indication relay 36-iRWK, to be described, to terminal N of the battery. Relay lNP is provided with a stick circuit which extends from terminal B of the battery over front conta-ct b of relay 35LC or over front contact b of relay 36LC to multiple connection terminal B191, front contact b of relay ilNP, back contact c of relay IRP, the winding of relay lNP, and over front contact a of relay iNP to terminal N of the battery. Relay INP is thus picked up when push button INPB is depressed, relay SSLC is picked up, and reverse switch indication relay- SS-RWK is picked up; or when button lNPB is depressed, relay sLC is picked up and reverse switch indication relay S-ERWK is picked up. Relay 1N? when thus energized is maintained picked up by its stick circuit so long as relay lRP remains deenergized and relay SSLC or relay 36LC remains energized.

Relay lRP has a pickup circuit extending from terminal B of the battery over back contact n of push button lRPB, terminal A191, the winding of relay lRP, multiple connection terminal BH2, and thence over a multiple circuit comprising two branches, the rst branch eX- tending from terminal BiiiZ over front contact c of relay 35LC, and over the back point of contact b of relay SS-IRWK to terminal N of the battery; and the second branch extending from terminal B102 over front contact c of relay 36LC, and over the back point of contact b of relay 36-lRWK to terminal N of the battery. Relay lRP is provided with a stick circuit which extends from terminal B of the battery over front contact b of relay SSLC or over front Contact b of relay 36LC to' multiple connection terminal Bitti, front contact b of relay lRP, back Contact c -of relay lNP, the winding of relay LRP, and over front contact a of relay IRP to terminal N of the battery. Relay IRP is thus picked up when push button ILRPB is depressed, relay 3SLC is energized and reverse switch indication relay SS-IRWK is deenergized; or when push button lRPB is depressed, relay 36LC is energized and reverse switch indication relay SG-RWK is deenergized. Relay RP when thus energized is maintained picked up by its stick circuit so long as relay lNP remains deenergized and relay 35LC or relay 36LC remains energized. The circuits con- 9 trolled by contacts of relays 1NP and IRP will be described later in this description.

There is shown in FIG. .'b, two push buttons designated by the reference characters kZRPB and ZLPB, respectively. Push button ZRPB is the right signal control push button for initiating controls for operating signal or signals 2R at each lield location for governing train movements to the right, and push button ZLPB is the left signal control push button for initiating controls for operating signal r signals 2L at each eld location for governing train movements to the left. These push buttons are also mounted on the control panel and are of the three position push-pull type with spring return to the center or neutral position. That is, the Push buttons each have a normally open back contact which is closed only when the respective push button is depressed and a normally open front contact which is closed only when the respective push button is pulled. The spring arrangements on the push buttons return the buttons to, and normally maintain them in, their center positions in which no contacts are closed. The arrow heads shown on the extensions of the push buttons indicate the direction in which the push buttons must be operated in order to close the respective movable contact members against their respective stationary contact points.

Relays ZRP and 2LP shown in FIG. 3b are right and left repeater relays which are energized by pushing push buttons ZRPB and ZLPB, respectively, while relay 2NP is a normal repeater relay which is energized by pulling either said push button. Relays ZRP, 2LP and ZNP are also conventional type telephone relays similar to relays 35LC and 36LC previously described and no further description of the relays is considered necessary except to say that relays ZRP and 2LP are each provided with at least one make-before-break contact while no such contact arrangement is provided on relay 2NP.`

Terminals A112, A114 and A115 shown in FG. 3b, are terminals on the control panel similar to the previously described terminals having a numeral designation with a letter A prex. Terminal B169 is a multiple connection terminal similar to terminals B100, B101 and B102 previously described.

Only two signal control push buttons ZRPB and 2LPB are required on the control panel in the embodiment of my invention illustrated because there is only one set of signals'(2R and 2L) at each of the field locations 35 and 36. However, in 'actual practice two signal control buttons would be provided on the control panel for each set of signals at the eld location having the greatest number of sets of signals. Each of these push buttons would have associated therewith a relay similar to relay ZRP or 2LP and a relay similar to relay ZNP would also be associated with each set of signals. As previously set forth, it is apparent that the control panel or keyboard is thus designed to control all of the functions to be controlled at all of the lield locations. During the establishment of the controls Afor the field locations where a less than maximum number of functions are to be controlled, some of the control push buttons would not perform any function but are in excess of the number required for control of those locations.

Referring again to FIG. 3b, relay ZRP has a pickup circuit extending from terminal B of the battery over back contact a of push button ZRPB, terminal A114, the back point of make-before-break contact a of relay ZRP, the winding'of relay ZRP, multiple connection terminal B199, and thence over a multiple circuit including in multiple, a front contact d of each of relays SSLC and 3'6LC to terminal N of the battery. Relay ZRP has a stick circuit which extends from terminal B of the battery over the back point of contact a of relay ZNP, the front point of make-before-break contact a of relay ZRP, the winding of relay ZRP, terminal B169 and thence over front contacts d in multiple of relays SSLC and 36LC to terminal N of the battery. It is thus apparent that relay ZRP is picked up when push button ZRPB is depressed and relay SSLC or 36LC is energized, and sticks up over its stick circuit, including the front point of its own contact a, so long asrelay ZNP remains released and relay 35LC or 36LC remains energized. Make-beforebreak contact a of relay ZRP insures that relay ZRP will bemaintained picked up when Contact a, transfers from its back to its front contact points in the closing of its stick circuit.

Relay 2LP has a pickup circuitextending from terminal B of the battery, over back contact a of push button ZLPB, terminal A115, the back point of make-beforebreak contact a of relay 2LP, the Winding of relay 2LP, terminal B109, and thence over a circuit including, in multiple, the front contacts d of each of relays 35LC and 36LC to terminal N of the battery. Relay 2LP has a stick circuit which extends from terminal B of the battery over the back point of contact a of relay ZNP, the front point of make-beore-break contact a of relay 2LP, the winding of relay ZRP, terminal B109, and thence over front contacts d in multiple of relays SSLC and 36LC to terminal N of the battery. It thus readily appears that relay ZLP is picked up when push button ZLPB is depressed and relay 35LC or relay 36LC is energized, and, is maintained picked up by its stick circuit including the front point of its own contact a, so long as relay ZNP remains released and relay 5LC or 36LC remains energized. Make-before-break contact a of relay 2LP insures that relay 2LP will be maintained picked up during the transfer of the contact a from its back Contact point to its front contact point` Relay ZNP has a multiple pickup circuit extending from terminal B of the battery over front contacts b, in multiple, of each of push buttons ZRPB and ZLPB, terminal A112, the winding of relay 2NP, terminal B109, and thence through the multiple circuit including a front contact d of each of the relays 35LC and 36LC, in multiple, to terminal N of the battery. Relay ZNP has a stick circuit which extends from terminal B of the battery over the front point of its own contact a, back contact b of relay ZRP, back contact b of relay 2LP, the winding of relay ZNP to terminal B109 and thence over the multiple circuit previously traced, including front contacts d of relays SSLC and 36LC, to terminal N of the battery. It is readily seen that relay ZNP is picked up by pulling push button ZRPBor ZLPB when relay BSLC or relay 36LC is energized, and is maintained picked up by its stick circuit including the front point of its own contact a so long as relays ZRP and 2LP remain released and relay SSLC or 36LC is energized. The circuits controlled by contacts of relays ZRP, 2LP and ZNP will be described later on in this description.

Referring now to FIG. 3c, there is shown the arrangement of circuits and apparatus for storing a code start for transmission of control codes to eld locations through the Form 514 code control system previouslyv mentioned. A spring return push button designated by the reference character STPB and having a normally open back contact a and al normally closed back contact yb is provided on the control panel for initiating and cancelling, respectively, code starts. Contact a of push button STPB operates in a manner identical to contact a of push button CPB previously described and no further description thereof is necessary except to say that contact a is closed when push button STPBis depressed. Contact b of push button STPB is normally closed and is opened by the pulling of the push button, as designated by larrow head on the extension of the push button at the movable portion of contact b. When the push button is released the spring return feature thereof returns contact Z1 to its normally closed position as shown.

Relay STP shown in FIG. 3c is a start repeater relay which repeats the manipulation of push button STPB as will be hereinafter described. Relays ZSSST andl 236ST are the start relays for storing a start for transmission of control codes to eld stations 235 and 236, respectively. These relays correspond to relay 234ST shown in circuit diagram drawing D-2547, sheet 14A, located in the back of the aforesaid Manual No. 514 of the Union Switch & Signal Division of Westinghouse Air Brake Company of Swissvale, Pa. lt is to be understood that one of these start relays is employed in the control oice for each field location controlled from the control panel, but, as only two such locations are employed in the specific example of my invention described herein, l have shown only the two start relays necessary for the example illustrated. It is believed readily apparent that when additional eld locations are controlled from the control panel, the additional necessary start relays provided with be arranged in a manner similar to relays 235ST and 236ST shown in FIG. 3c, and controlled in a manner similar to said relays as described below.

Terminals A150 and A151 are terminals on the control panel similar to terminals A160 and A1111 shown in FIG. 3a and described above. Terminal A111 shown by dotted lines in FIG. 3a is the identical terminal A111 shown by solid lines in FlG. 2 and is thus shown in order that the circuit connections to terminal A111 may be described. Terminals B211 and B212 are multiple connection terminals similar to terminals B160, B101 and B102 shown in FIG. 3a. Terminals SA and 17A in FIG. 3c are terminals on the oflice line coding unit for the Form 514 code communication system employed in my invention and said terminals 8A and 17A correspond to terminals 3A and 17A shown on aforesaid circuit drawing D-2547, sheet 14A. Reference is made to aforesaid Manual No. 514 and to the said circuit drawing in said manual for a complete understanding of the operation of the internal circuits in the said office line coding unit and connected therein to said terminals 8A and 17A.

Relay STP has a pickup circuit which extends from terminal B of the battery over back contact a of push button STPB, terminal A150, and through the winding of relay STP to terminal N of the battery. Relay STP has a stick circuit which extends from terminal B of the battery over front contacts f of reays 35LC and 36LC, in multiple, multiple connection terminal B211, the back point of contact b of relay MP, to be described, front contact a of relay STP and through the winding of relay STP to terminal N of the battery. Relay STP is thus picked up whenever push button STPB is depressed and is maintained picked up as long as relay MP remains released and one of the location selection relays remains energized.

The location selection storage cancellation circuit connected to terminal A111 as shown in FIG. 3c extends from terminal B of the battery over front contacts f of relays 35LC and 36LC, in multiple, terminal B211, the front point of contact b of relay MP, and front contact b of relay STP to terminal A111. It is thus apparent that section location storages on the control panel are cancelled when relay MP is picked up as will be described later in this description. Relay STP, as indicated by the arrows drawn through the movable members of the contacts of the relay, is made slightly slow release to insure that relay MP closes the front point of its contact b before front contact b of relay STP opens. This insures that the cancellation circuit to terminal A111 is completed when the stick circuit over the back point of contact b of relay MP to relay STP is opened by the picking up of relay MP.

Relay 235ST in FIG. 3c has a pickup circuit which extends from terminal B of the battery yover front contact c of relay STP, multiple connection terminal B212, front contact e of relay 35LC, the winding of relay 235ST, terminal A151, and back contact b of push button STPB to terminal N of the battery. Relay 235ST has a stick circuit including two branches, the first branch extending from terminal B of the battery over the back point of make-before-break contact c of relay 2358, to be described, to front contact a of relay 235ST, and the second branch extending from terminal 8A over the front point of make-before-break contact c of relay 2355 to front contact a of relay 235ST, and thence through the winding of relay 235ST to terminal A and over back contact b of push button STPB to terminal N of the battery. Relay 235ST is thus picked up when relay STP picks up and location selection relay 35LC is energized, and is maintained picked up until push button STPB is pulled or until relay 235s is energized and energy is removed from terminal 8A of the oilice line coding unit.

Relay ZSGST shown in FIG. 3c has a pickup circuit which extends from terminal B of the battery over front contact c of relay STP, terminal B212, front contact e of relay 36LC, the winding of relay 236ST, control panel terminal A151, and over back contact b of push button STPB to terminal N of the battery. Relay 236ST has a stick circuit including two branches, the iirst Ibranch extending from terminal B of the battery over the back point of make-before-break contact c of relay 2368, to be described, to front contact a of relay 236ST, and the second branch extending 'from terminal SA over the front point of make-beore-break Contact c of relay 2363 to front contact a of relay 236ST, and thence through the winding of relay 23681 to terminal A151 and over back contact b of push button STPB to terminal N of the battery. Relay 236ST is thus picked up when rel-ay STP picks up and is maintained picked up until push button STPB is pulled or until relay 2365 is energized and energy is removed from terminal 8A of the office line coding unit. Relays 235ST and 236ST operate in a manner similar t-o relay 23481 shown in said drawing D2547, sheet 14A in said Manual No. 514, and reference is made to said Manual for a complete understanding of the operation of the ST relays and the circuits controlled thereby, these relays themselves lforming no part of my present invention but being shown in order to make the specication complete.

It is deemed expedient to discuss at this time the ap.- paratus shown in FIGS. 4b, 4c and-4d Ibefore further description of the apparatus arrangement of my invention is given. Relay MP shown in FIG. 4b corresponds to relay MP shown in the lower left-hand portion of said drawing D-2547, sheet 14A, and operates in a manner identical to said relay. Relays 235D and 236D in FIG. 4c are similar to relay 234D shown on the right-hand side of sheet 14A of said drawing D-2547. Relays 2358 and 2368 shown in FIG. 4d are similar to relay 2348 shown in the lower right-hand portion of said sheet 14A. These relays shown in said FIGS. 4b, 4c and 4d form no part of my present invention but are shown in order to make this specification complete. It is `considered sutcient for purposes of this description to point out that relay MP is the master relay repeater relay employed to repeat the M orl master relay of the code communication system. The M relay and thus the MP relay are energized when a control code is to be transmitted by the code system. Relays 235D and 236D are the delivery relays for the code control communication system and pick up to deliver information, received from the respective field location, to the proper indication relays as will be more apparent later in this description. Relays 235S and 2365 are t'ne station call relays for ield stations 235 and 236 and select the respective station determined by the code combination transmitted by the code control communication system. Reference is made to aforesaid Manual No. 514 fora more complete understanding cf the operation of relays MP, 235D, 236D, 2358 and 236s. l

The code communication circuits for transmitting `control codes to the field locations are'shown schematically in FIG. 4a. Relays 35-1NRWSR, 35-2LHSR, $5- ZRHSR, and 35-1TKSPR are located at eld location 35 which is assigned to field station 235 in the code com- 13 munication system. These relays correspond to relays NRWSR, LHSR, RHSR and TKSPR, respectively, shown in drawing D-2547, sheet 15A, in the back of the aforementioned Manual No. 514. Relays 36-1NRWSR, 36-2LHSR, 36-2RHSR and 36-1TKSPR are lo-cated at lield location 36 which is assigned to eld station 236 in the code communication system. The correspondence between these relays and the similar relays shown on sreet 15A of said drawing D-2547 is readily apparent.

Relays 35-1NRWSR and 36-1NRWSR comprise the nal stick relays at the eld locations for controlling switches Z55-1W and 36-1W respectively, to normal and reverse positions. Relays 35-2LHSR, 36-2LHSR, 35-2RHSR and 36-2RHSR comprise the nal stick relays at the eld locations for controlling the clearing of left and right signals, respectively, at the field locations. ilese relays are of the magnetic stick type the contacts of which are Ioperated to first and second positions by an mpuse of energy of one polarity or another through their control windings and which remain in the last oper..ted position without energy. Such relays are well known in the art and no further description thereof is necessary. Relays SS-ITKSPR and 36-1TKSPR are conventional neutral relays which are employed in the field to repeat the occupied or unoccupied condition of track sections 35-1T and E56-1T, respectively, represented on the track diagram in FIG. la. These relays are energized and deenergized respectively when their associated track sections are unoccupied or occupied.

The circuit arrangement shown on the left-hand side in FIG. 4a shows the arrangement at the contr-ol oiice for controlling the transmission of control codes to the e'd location. As is apparent, contacts of NWK, RWK, LHK and RHK indication relays are employed to control the transmission of the control codes. The indication relays, contacts of which are shown in drawing FIG. 4a, will be described hereinafter.

The dotted lines between the two sets of terminals shown in FIG. 4a, represent the Form 5l4code control communication system previously mentioned and employed in this example of my invention, and no details of this portion of the code control communication system need be shown. The terminals to the left of the dotted lines represent terminals on the otlice line coding unit,

and the terminals to the right ot the dotted lines represent terminals on the eld line coding units. These units are shown on sheets 14A and 15A, respectively of drawing D2547 in the aforesaid Manual No. 514.

The code control communication system in the example shown in this description operates in the identical manner to the communication system shown and described in said Manual No. 514, and it is, therefore, considered suflicient for purposes of this description to point out that the code system will transmit a code for controlling a `switch control relay to a tirst position for controlling a switch to its reverse position when positive energy is supplied to terminal 3A of the oice line coding unit. Similarly, the code system will transmit code for controlling a switch control re`ay to a second position for controlling a switch to its normal position when positive energy is supplied to terminal 1A of the oce coding unit. Likewise, the code system will transmit a code for controlling signal control relays to a tirst position for' clearing of .signals when positive energy is supplied to terminals A or 7A, and will transmit a code to control the signal control relays to av second position for controlling signals to stop [when no energy is supplied to said terminals 5A or 7A.-.

The circuit for supplying positive energy to terminal 3A for controling switch control relay 35-1NRWSR to its said rst position, extends from terminal B of the battery over front contact d of station call relay 235S, the front point of contact c of relay 35-1RWK, to be described, and front contact b of relay SS-INWK, to be described, to `terminal 3A. The circuity for supplying Vpositive energy to terminal 1A for controlling -switch control relay 35-1NRWSR to its said second position extends from terminal B of the battery over front contact d of relay 2358, the back point of contact c of relay 35-1RWK, and back contact c of relay 351NWK to terminal 1A.

The circuit for supplying positive energy to terminal 5A for controlling signal control relay SS-ZLHSR to a position for clearing signal 35-2LA or SS-ZLB extends .from terminal B of the battery over front contact e of relay 2358, the front point of Contact g of relay 35-2LHK to be described, and back contact g of relay SS-ZRHK, to be described, to terminal 5A. The circuit for supplying positive energy to terminal 7A for controlling signal control relay SS-ZRHSR to a position for clearing signal 3S-2R extends from terminal B of the battery over front Contact e of relay 2358, the back point of contact g of relay 35-2LHK, and the front point of contact h of relay 35-2RHK to terminal 7A.

The circuit for supplying positive energy to terminal 3A for controlling switch control relay 36-1NRWSR to its said trst position extends from terminal B of the battery over front contact d of station call relay 236s, the front point of contact c of relay 36-1RWK, to be described, and front contact b of relay 36-1NWK, to be described, to terminal 3A. The circuit for supplying positive energy to terminal 1A for controlling switch control relay 36-1NRWSR to its said second position extends from terminal B of the battery over front contact d of relay 236s, the back point of contact c of relay 36-1RWK, and back contact c of relay 36-1NWK to terminal 1A.

The circuit for supplying positive energy to terminal 5A for controlling signal control relay 36-2LHSR to a position `for clearing signal 36-2L extends from terminal B of the battery over front contact e of relay 2368, the front point of contact g of relay 36-2LHK, to be described, and back contact g of relay 36-2RHK, to be described, to terminal SA. The circuit for supplying positive energy to terminal 7A for controlling signal control re'ay SG-ZRHSR to a position for clearing signals 36-2RA or 36-2RB extends from terminal B of the battery over front contact e of relay 2368, the back point of contact g of relay 36-2LHK, and front contact h ofV relay 36-2RHK to terminal 7A.

Referring now to FIG. 5, there is shown the switch indication circuits at field locations 35 and 36 and the switch indication relays in the control oice. The terminals shown to the right of the arrows are terminals on the eld line coding units at the respective eld locations and the circuits shown on the right-hand side of the drawing are the circuits 'for controlling the indications to be transmitted. Relays BS-INRWSR and 36-1NRWSR, contacts a of which are shown at the field locations in FIG. 5, are the switch control or final stick relays shown in FIG. 4a, as previously mentioned, for controlling the movements of switches 35-1W and 36-1W to normal and reverse positions. Relays 35-1NWCR, 35-1RWCR, 36- INWCR and 36-1RWCR, the windings and contacts of which are shown at the tield locations in FIG. 5, are switch correspondence or repeater relays which reect the correspondence between the positions of switch control relays SS-INRWSR and 36-1NRWS'R and the positions of the respective switches 35-1W and 36-1W at field locations 35 and 36, respectively. The control circuits to the windings of these relays are not shown in the drawings but relays 35-1NWCR and 36-1NWCR may be controlled, for example, in a manner similar to relay 3NWC shown in FIG; lb of Letters Patent of the -United States No. 2,532,832, issued December 5, 1950, to

relays forms no part of my present invention, it is ,con-v sidered sufficient for purposes of this description to point out that contacts a and b of relays 351NWCR and 36-1NWCR are picked up only when switches 35-1W and lid-1W, respectively, and relays 35-1NRWSR and StS-INRWSR, respectively, occupy normal positions. Contacts a and b of relays SS-IRWCR and 36-1RWCR are picked up only when switches 35-1W and Sti-1W, respectively, and relays 35-1NRWSR and SG-INRWSR, respectively, occupy reverse positions. Switches 35-1W and 36-1W, and control relays SS-NRWSR and 36- lNRWSR, being assumed to normally occupy their normal positions, the contacts of relays 35-1NWCR and 36- lNWCR are shown picked up, and the contacts of relays 351RWCR and 36-1RWCR are shown released in FIG. 5.

Terminals 9A and TiA in FG. 5 are terminals on the otiice line coding unit in the control oiiice. The dotted lines shown between the terminals on the oiiice line coding unit and the iield line coding units represent the Form 514 code control communication system employed in the present illustrated example of my invention. Terminals 9A and 11A are multiple connection terminals as is apparent in FIG. and correspond to terminals 9A and ltiA, respectively shown on the right-hand side of sheet 14A of drawin-g D-2547 in aforesaid Manual No. 514.

Relays 35-1NWK and 36-1NWK are the -switch indication relays at the control ofiice which indicate respectively the normal position of switches v:i5-1W and 36-iW and the corresponding position of their control relays at held locations 35 and 36, respectively. Similarly, relays SS-RWK and 36-1RWK are switch indication relays indicating, respectively, the reverse position of switches .3S-1W and E36-1W and the corresponding position of their control relays at the said field locations. As previously stated, switches 35-lW and S56-1W, and relays 35-1NRWSR and 36-1NRWSR, being assumed to normally occupy their normal positions, relays 35-1NWK and SG-INWK are shown normally picked up and relays SSJRWK and St-IRWK are shown normally released.

Relay SS-TLNWK has an indication pickup circuit extending from terminal 5A of the oiice line coding unit over the front point of makebefore-break contact a of relay 235D and through the winding of the relay to terminal N of the battery. Relay SS-NWK has a control pickup circuit extending from terminal B of the battery over front contact d of relay IRP, multiple connection terminal BZN, to be described, front contact g of relay SLC and through the winding of relay 35-1NWK to terminal N of the battery. Relay 35-1NWK has a iirst stick circuit extending from terminal B of the battery over the back point of make-before-break contact h of relay SSLC, front contact a of relay 35-1NWK, the back point of make-before-break contact a of relay 235D, and through the winding of relay SS-lNWK to terminal N of the battery. Relay SS-INWK has a second stick circuit extending from terminal B of the battery over back contact d' of relay INP, multiple connection terminal B211, to be described, the front point of make-before-break contact h of relay SSLC and Ithence over front contact cz of relay SS-INWK and through the remainder of the tirst stick circuit for relay 35-1NWK, just described, to terminal N of the battery.

Relay 35-1RWK has an indication pickup circuit extending from terminal 11A of the o-iiice line coding unit over the front point of make-before-break contact b of relay 235D, and through the winding of relay SS-IRWK to terminal N of the battery. Relay SS-RWK has aV control pickup circuit extending from terminal B of the battery over fro-nt contact e of relay IRP, multiple connection terminal B212, to be described, front contact k or" relay SSLC, and through the winding of relay 35` lRWK to terminalV N of the battery. Relay Sii-IRWK has a first stick circuit extending from terminal B of the battery over the back point of make-before-break contact .lt of relay SSLC, fro-nt contact a of relay SS-RWK, the back point of make-before-break Contact b of relay 235D and through the winding o-f relay SS-IRWK to terminal N of the battery. Relay SS-IRWK has a second stick circuit extending from terminal B of the battery over back contact d of relay INP, terminal B211, the front point of make-before-break contact h of relay 35LC and thence over front contact a of relay 35-1RWK and through the remainder of the first stick circuit for relay SS-lRWK, just described, to terminal N of the battery.

Relays .SG-INWK and 36-1RWK have pickup and stick circuits similar to those just described for relays 35-INWK and SS-IRWK, respectively, `except including contacts of relays 36LC and 236D and their own front contacts a, and no detailed tracing of these circuits is considered necessary.

Terminals B210, 1321i and B212 are multiple connection terminals to which, in actual practice, controi pickup circuits for the indication relays for each first switch at all field locations are connected, but, only two field locations being illustrated in this described example of my invention, only the control pickup circuits for the indication relays for switches 35-1W and 35-1W are shown in FIG. 5. It is also desired to point out that additional indication pickup circuits are, in actual practice, connected to terminals 9A and 11A for control of indication relays for each first switch at all iield locations. However, these circuits are also not shown :because in the illustrated example of my invention only two field locations are shown.

The operation and purpose of the circuits shown in FIG. 5 will become more apparent later in this specification in the description of a specific example ot' the ycontrol of one of the switches shown on the track diagram in FIG. 1a.

FIGS. 6 and 7 show the signal indication circuits at the ield locations and the signal indication relays at the control oiiice. The terminals shown to the right of the arrows are terminals on the lield line coding units at the respective field locations and the circuits shown on the right-hand side of the drawings are the circuits for controlling the indications to be transmitted. Relays 35- ZLHSR and SS-ZRHSR, contacts a and b of which are shown in FIG. 6 at the field location 35, are the final stick relays shown in FIG. 4a for controlling the clearing of signals SS-ZLA and 35-2LB, and 35i-2R, respectively. Relays 36-2LHSR and SG-ZRHSR, contacts a and b of which are' shown' in FIG. 7 at the field location 36, are the final stick relay shown in FIG. 4a for controlling the clearing of signals 36-2L and 36-2RA and 362RB, respectively. y

Relays 352LRGPR and 35-2RRGPR, the windings and contacts a of which are shown at tield location 3S in FIG. 6, are signal repeater relays which reiiect the condition of signals SS-ZLA and 35-2'LB, and SaS-2R, respectively. The control circuits for the windings of these relays are not shown in the drawings, but such signal repeater relaysand their operation are well known in the art. Relay 35-2RRGPR may be controlled for example in a manner similar to relayrLSSRP shown in FIG. 1b of Letters Patent of the United States.- No. 2,580,150, issued December 25, 1951 to Earl M. Allen for Route Circuit Network Control Apparatus for Railway Signals. It is considered suicient for purposes of this description to point out that back contact a of relay SSL-ZLRGPR is open when both signals 35-2LA and 35-2LB indicate stop, and said contact 'a is closed when either of said signals is cleared for a train movement to the left. Similarly, contact a of relay SS-ZRRGPR is picked upV and opens when signal 3'5-2R indicates stop, and said contact a is released and closed when said signal is cleared for a train movement to the right.

Relays 36-2LRGPR and 36-2RRGPR shown at eld location 36 in FIG. 7 are signal repeater relays similar to those described above. These relays reect the condition of signals 36-2L, and 36-2RA and 36-2RB, respectively. Back contact a of relay 36-2LRGPR is open when 17 signal 36-2L indicates stop, and said contact a is closed when said signal is cleared for a train movement yto the left. Back contacta of relay 36-2RRGPR is open when both signals 36-2RA and 36-2RB indicate stop, and said contact u is closed when either of said signals is cleared rfor a train movement to the right.

Relays 35-2LASR and 35-2RASR shown in FIG. 6, and relays 36-2LASR 'and 36`2RASR shown in FIG. 7 are approach locking relays for signals 35-2L and 35-2R, and 36-21L and 36-2R, respectively. The windings and contacts a of these relays are shown in FIGS. 6 and 7 but the control circuits for the windings of the relays are not shown. Such approach locking relays and their operation are well known in the art. Relay 3'S-2LASR may he controlled, for example, in a manner similar to relay LSSALS shown in FIG. lb of aforesaid Earl M. Allen Patent No. 2,580,150. It is deemed sufficient for purposes of this description to point out that such relays are normally picked up, and lare released when a control code is received at the respective field location for clearing the respective signal or signals. That is, relay 3S-2LASR is released when a control code is received at field location 35 for clearing signal 35-2LA or SS-ZLB. Relay 35-2RASR is released when a control code is received for clearing signal 35-2R. Similarly, relay 362LASR is released when a control code is received at field station 36 for clearing signal 36-2L, and relay 36-2RASR is released when. a control code is received for clearing signals 36-2M or 36-2RB. When an approach locking relay is released and a control code is received for controlling the respective signal to indicate stop, the relay is not picked up until the expiration of a predetermined time delay.v This time delay period is often termed the in time period of a signal and, as will be described in more detail later in this description, an in time indication is transmitted from the respective field location to the control oliice.

Terminals 13A and 15A in FIG. 6 are terminals on the oliice line coding -unit in the control oce. These terminals are also shown by dotted lines in FIG. 7 and it is believed readily understood that they are multiple connection terminals and that both sets of terminals shown are, therefore, the same terminals. The dotted lines shown between the terminals on the office line coding unit and the ield line coding units represent, yas before the Form 514 code control communication system employed in illustrating and describing my invention. Terminals 13A and 15A in FIGS. 6 and 7 correspond to terminals 13A and 15A respectively, shown on the right-hand side of sheet 14A of drawing D-2547 in aforementioned Manual No. 514 which describes said Form 5.14 code control system.

' Relays SS-ZLHK and f35-2RHK (FIG. 6) are the signal indication relays at the control oflice which indicate respectively, the condition of signals 35-2LA and 35-2LB, and signal 35-2R. Similarly, relays 36-2LHK and 36-2RHK (FIG. 7) are the signal indication relays at the control ollice which indicate respectively the condition of signals B16-2L, and 36-2RA and 36-2RB. Relays 3S2RHK and 36-2LHK are picked up to indicate that their respective signals are cleared, and relays 35-2LHK and 36-2RHK are picked up to indicate that their respective signals 'are cleared. Signals 35-2LA, 35-2LB, 3S-2R, S56-2L, 36-2RA and 36-2RB, illustrated on the track diagram in FIG. 1a, are assumed to normally be at stop and, therefore, the said signal indication relays are all shown released. Relays 35-2HK and `362HK are auxiliary signal indication relays, the purpose of which will become apparent later in this description.- These relays are also normally released as shown.

Terminals B200 through B206 shown in FIG. 6 are multiple connection .terminals to which the signal indication relays for each first set of signals at all field locations are connected. However, only two field locations being illustrated in the present described example of my inven- 18 tion only two sets of signal indication relays are shown' connected to said terminals, and these multiple connec` tions are illustrated by showing said terminals by dotted lines in FIG. 7 of the drawings. that the terminals B200 and B206 shown in this manner in FIG. 7 represent the same terminals B200 `through` B206 shown by solid lines in FIG. 6.

Relay 35-2LHK has an indication pickup circuit whichv extends from terminal 13A on the office line coding unit over the back point of contact e of relay 35-2RHK, the front point of make-before-hreak contact c of relay 235D, and through the winding of relay 35-2LHKto terminal N of the battery. Relay 35-2LHK has an indication stick" circuit extending from said terminal 13A over the frontpoint of contact e of .relay 35-2RHK, the front point of contact e'of relay SS-ZLHK, the `front point of makebefore-break contact c of rel-ay 235D, and through Vthe-` winding of relay 35-2LHK to kterminal Nof the battely.

Relay 352LHK has a first control pick-up circuit 'ex'- tending from terminal B of the battery over front com' tact b of relay 2NP, terminal B200, front contact l of' relay SSLC, the front point of contact d of'rel'ay 35 ZRHK, and through the winding of rel-ay 35-2LHK tov Relay 35-2LHK has a control stick circuit comprising" three branches, the iirst branch extending from terminal B of the battery over the back point of make-beforehreak contact Vn of relay 35LC to front contact a of re' lay SS-ZLHK; the second branch extending from terminal B of the battery over the back point of contact c of re lay 2RP, terminal B202, the front point of make-beforebreak contact n of relay SSLC to front contact a of re` lay SS-'ZLI-IK; and the third branch extending from terminal B of the battery over front contact o of relay SSLC, back contact b of relay 35-2RHK to front contact aof 're'-4 lay 35e2LHK where all three branches merge'an'd -ext'nd over front contact a of relay 35-2LHK, the back pointV of make-before-break contact c of relay 235D,' and througlrl the winding of relay 35-2LHK to terminal N'of the battery. g Relay 35-2RHK has an indication pickup circuit ex` tending from terminal 15A of the oliice line 'codingfunit over the back point of contact fof relay 35-2LHK, the front point of makel-before-break contact d of relay 235D,` and through the winding of relay 35-2RHKto terminal N of the battery. Relay 35-2RHKhas an indication" stick circuit extending from said terminal 15A over they front point of contact y of relay 35-2LHK,' the front point of contact f of relay BS-ZRHK, the front point .of make-before-break contact d of relay 235D, and through the winding of relay 35-2RHK to terminal Noi the battery,

Relay' 35-2RHK has a first control pickup circuit extending from battery terminal- B over front contact c of relay 2NP, terminal B203, front contact p of relay BSLC, the front point of contact d of relay 35-2LHK and through the Winding of relay 35-2RHK to battery terminal N. Relay 35-2RHK, has a second control pickup circuit extending from battery terminal B over the. front point of contact c of relay ZRP, terminal B204, front contact r of relay 35LC, the back point of contactv d of relay 35-2LHK, and through the winding of rela 35-2RHK to terminal N of the battery.

Relay 35-2RHK has a control stick circuit comprising three branches, the first branch extending from battery terminal B over the b ack point of make-beforefbreak contact s of relay 35LC to front contact a 'of relay 35-1 ZRHK; the second branch extending from battery'terminall.

It is to be understood.

the third branch extending. from terminal B ofthe battery over'front contact o of relay SiSLC, the back point of contact b of-relay 3S-2LHK to front contact a of relay 35-2RHK where all three branches merge and extend over front contact a of relay 35-2RI-lK, the back point of make-before-break contact d of relay 235D, and through the winding of relay 35-2RHK to battery terminal N.

Relay 35-2HK has two indication pickup circuits, the rst extending from terminal 13A on the oiiice line coding unit over the front point of contact e of relay 35- ZRHK and over the back point of contact e of relay 35- ZLHK to the front point of make-before-break contact e of relay 235D, and the second extending from terminal 15A`on the ofce line coding unit over the front point of contact f of relay BS-ZLHK and over the back point of contact of relay SS-ZRHK to the vfront point of make-before-break contact e of relay 235D, 'where'the tending from battery terminal B over its own front con` tacta, the back point of make-beforebreak contact e of relay 235D', through thewinding of relay 35-2HK and thence through said back contacts e of relays 35-2LI-IK and SS-ZRHK in multiple, and over its own front Vcontactb to terminal N of the battery. Y

Relays 36-2LHK, 36-2RHK and 36-2HK shown in FIG. 7 have pickup and stick circuits similar to those just described for relays SS-ZLHK, SS-ZRHK and SS-ZHK,

respectively, except including contacts of'relays '36LC and 236D and their own contacts a and b and no detailed tracing of these circuits is considered necessary.

.As hereinbefore stated, I utilize, in my invention, the above described indication relays as controlstorage or memory relays, in addition to their usual use as indication relays. I will now describe in' general terms the manner in which said relays are actuated to store eld function commands or controls, and will later set forth specific examples of theoperation of some of the relays in their employment as both eld function vcontrol storage relays and eld function indication relays.

` In the usual codeV control communication system two neutral relays, such as SS-INWK and 35-1RWK shown in FIG. 5,'are employed for indicating the two extreme positions of a switch, and one or the other of the relays is picked up to indicate said switch positions. Both relays arerele'ased at the same time only when the switch is in transit from one position to the other, and in the usual systems the two relays are never picked up at the same time. By providing control means for picking up both relays at the same time, it is apparent that a combination is available for establishing a controlfor operating the switch to oneextreme position; and, by maintaining both relays picked up,- this control can be stored until it per-r formsits desired function, that is, the operation of the switch to said one extreme position. Similarly, by providing controlmeans for releasing both relays at the same time, it is apparent thata combination is available for establishing a control for operating the switch to the other extreme position; and, by maintaining both relays released, this control can be stored until it performs its desired function, that is, the operation of the switch to said other extreme position. Usually a true switchintransit indication is provided bythe released combination of both said indication relays. By employing this combination of said relays for storing acontrol for operating the switch to onev extreme position', as set forth above, it at first appears that' no means is now available for providing a switch-intransit indication.

switch actually being in transit, the said released combination of both indication relays can continue to be employed for providing the switch-in-transit indicationA when said both relays are released, and the above-described picked-up combination of kboth relays can be employed for providing said indication when both relays are picked up. Accordingly my invention providesL circuits and apparatus arrangements for accomplishing the desired operation described. This arrangement will become more apparent in the specic examples of the operation of my invention set forth hereinafter in this description.

Two neutral relays, such as relays SS-ZLHK and 35- ZRHK shown in FIG".l 6 of the drawings, are employed in the usual code control communication systems forindicaring the condition of opposing signals. Both relaysare normally released to indicate the normal or stop condition ofthe signals and each are picked up in said signal systems whentheir respective signals are cleared. Because opposing signals cannot be cleared at the same time the pickedup combination of both signal indication relays is employed in said usual systems to indicate when the signals are in time which occurs, as previously explained, when a signal is cleared and then manually controlled to its stop condition. By providing control means for picking up each said relay when it is desired to clear its respective signal, and maintaining the picked-up relay in said position, means are provided for establishing and storing a signal control to be transmittedto the respective field location. However, it now appears that there are no means at the control olice to respond to a signal clear indication being received from the iicld location. Accordingly, in my invention l have provided an additional signal indication relay, such as relay 35-2HK in FlG. 6 of the drawings, for each set of opposing signals. These relays are so arranged as to be picked up when either left or right signals are cleared and, in combination with a controlled picked-up condition of the LHK or RHK relay, an indication can bc provided to indicate which signal is cleared. The picked-up condition of both LHK and RHK relays can continue to be employed for giving an in-time indication as hereinafter described.

As discussed in general terms above, l thus provide in my invention means whereby the usual signal indication relays for a set of signals can be employed to store signal controls to be transmitted to the eld location of said signals, and in conjunction with one additional relay (HK) for cach set of signals, the usual signal indication relays can continue to be employed for indicati-ng the cleared conf. dition of the signals. The arrangement to accomplish this operation will become more apparent in the descrip.

tion of the specific examples of the operation of my invention set forth hereinafter in this specification. y

Having thus set fortliin general terms the principal features of my invention, I will now, describe the operation of the circuit and apparatus arrangements shown in the drawings by specificexamples of the selection of a tield location; the establishing, storing and transmitting of controls for performing several functions at the selectedlocation; and the receiving of indications from said location of the performance of the controlled functions'.

All apparatus is shown inthe drawings in its normal condition. Assuming that it is' desired to clear signal 35-2LB, shown in FIG. lo, at field location 35 (field station 235), for a train movement out of the siding in the' over its previously described pickup circuit including back,

contacts of push buttons SDPBA and'SP-B, the relay will However, if establishing and storing a' switch control will be assumed to be equivalent to the 21 pick-up, and,lthe buttons being stick push buttons as previously described, relay SSLC will temporarily remain picked up. Field location 35 has thus been selected.

The operator will now depress reverse switch control push button IRPB (FIG. 3a) and left signal control push button ZLPB (FIG. 3b) in that order. The depressing of push button IRPB momentarily closes back contact a of the button, and relay IRP is energized over its previously described pickup circuit including front contact c of location selection relay 35LC and the back point of contact b of relay vSiS-IRWK. Relay IRP accordingly picks up. The said front contact of relay 35LC prevents the establishment of the switch control before a field location has been selected. The said back contact of relay 35-IRWK permits the establishment of the reverse switch control only when the switch occupies its normal position or is in transit to its normal position. (Similarly the front point of contact b of relay SS-IRWK inthe previously described pickup circuit for relay 1NP permits the establishment of a normal switch control only when the switch occupies its reverse position or is in transit to its normal position.) Relay rIRI picks up as stated, and is maintained picked up over its previously described stick circuit including its own front contacts a and b, back contact c of relay INP and front contact b of relay 35LC. Back contact c of relay INP insures that the stick circuit for relay IRP is opened when a normal switch control is established, and, if relay IRP is picked up by the operator inadvertently depressing push button IRPB when he intended to push button INPB, the subsequent depressing of button INPB and picking up of relay INP will open the stick circuit for relay IRP at the open back contact c of relay INP, thereby releasing relay IRP. The negative terminal of the battery is connected to relay INP over the front point of contact b of relay 35-IRWK when relay IRP is up, due to relay SSJRWK being picked up by the picking up of relay IRP as will be hereinafter described. Front contact b of relay SSLC in the stick circuit for relay IRP opens the stick circuit, when the control panel is transferred for control of another iield location, or when the field location selection is manually cancelled or, as will appear hereinafter, after the controls have been transmitted to the eld location 35. (Front contact b of relay 3SLC also operates in a similar manner in the stick cir'- cuit for relay lNP.)

The depressing of push button 2LPB (FIG. 3b) as described, momentarily closes back contact a of the button and relay 2LP is energized over its previously described pickup circuit including front contact d of relay SSLC. Relay 2LP accordingly picks up. Front contact d of relay 35LC prevents the establishment of the signal control before a field location has been selected; and opens the stick circuit for relay 2LP, when the control panel is transferred for control of another field location, when the iield location selection is manually cancelled or, as Will appear hereinafter, after the controls have been transmitted to the field location 35. Relay 2LP picks up as stated and is maintained picked up over its previously described stick circuit including back contact a of relay ZNP and the front point of its own front contact a. This make-beforebreak contact a insures the establishment ofthe stick circuit for relay 2LP before the back point of contact a in the pickup circuit for the relay is opened. The back point of contact a of relay ZNP in the stick circuit for relay 2LP provides means for releasing relay 2LP if it had been inadvertently picked up by the operator depressing push button 2LPB incorrectly. (The back point-of contact a of relayZNP also provides means for releasing relay LRP under similar conditions.) The operation of relay ZNP will be discussed hereinafter in this description.

.As previously stated, all apparatus being assumed to be in its normal condition, switch SS-IW at field location 35 occupies its normal position and switch indication relay SS-INWK (FIG. 5), prior to the picking up of relay SSLC," is' held up over its previously described-stick circuit including the back point of contact h of relay 35LC. When relay 35LC is picked up as previously described, relay 3S-1NWK is continued to be held up by the circuit over the front point of contact h of relay 35LC and back contact d of relay INP. Said contact lz is a makcbefore break contact to insure the continued energization of relay SS-INWK when the said contact transfers from its back to its front contact point.- When relay IRP is picked up as described above, the control pickup circuit for relay 35-1RWK (FIG. 5) including front contact e of relay IRP and front contact k of relay 35LC, is completed and relay SS-IRWK picks up. The picking up of relay SS-IRWK establishes the stick circuit for that relay including its own yfront contact a and the front point of con-k tact h of relay 35LC. Back contact d of relay INP in the stick circuits for relays 35-1NWK and SS-IRWK provides the means for releasing both said relays to store a normal switch control when such a control is initiated by the depressing of push button INPB and the resultant pickup of relay INP.

As has previously been set forth the track diagram illustrated in FIG. lai is normally dark. However, as shown in FIG. lb the picking up of relay SB-IRWK completes an intermittent energizing circuit for the filament of indication lamp SS-IWRKE which may be traced from coded battery CB, previously described, over the front point of contact g of relay SS-INWK, front contact g of relay SS-IRWK and through the filament of said lamp to terminal N of the battery. Lamp 35-IWRKE thus commences flashing and indicates that a command or control has been storedfor controlling switch 35-IW to its reverse position (or that the switch is actually in transit to its reverse position as described later).

The picking up of relay 2LP as previously described completes the previously described control pickup circuit for relay 35-2LHK (FIG. 6) including the front point of contact c of relay 2LP, front contact m of relay SSLC and the back point of contact d of relay SS-ZRHK. Relay SS-ZLHK accordingly picks up and completes its previously described stick circuits including its own front contact a. n

The picking up of relay SS-ZLHK as described above completes an intermittent energizing circuit for the filament of indication lamp BS-ZLBAKB (FIG. 1b) which may be traced from coded battery CB over theback point of contact c of relay 35-2HK, the front point of contact-l of relay 3\5-2LHK, back contact k of relay 3\5'-2RHK, the front point of contact d of relay SS-IRWK and through the filament of said lamp to terminal N of the battery. Lamp 35-2LBKE thus begins to ash and indicates that a control has been stored for clearing signal 35-2LB.

The operator having selected the desired field location 35 and established the proper controls as outlined above, now depressesthe code start push button STPB (FIG. 3c) to establish and store a code start for field station 235 assigned to field location 35. The depressing of said push button closes the previously described pickup circuit for relay STP. Accordingly, relay STP picks up and closes its previously described stick circuit including its own front contact a, the back point of contact b of relay MP and front contact f of relay 35LC. Relay STP is accordingly temporarily maintained in its picked-up position, but released when relay MP picks up as hereinafter described. Front contact f of relay l35LC in the stick circuit for relay STP opens said stick circuit when the control panel is transferred for control of another field location or when the iield location selection is manually cancelled.

The picking up of relay STP closes at its front contact c the previously described pick-up circuit for start relay ZSSST including front contact e of relay 35LC; Relay 235ST accordingly picks up and completes its stick circuit including its own front contact a and the back pointof contact c of eldstation 235 call relay 2358.

Normally closed back contact b of push button STPB over which all start relays such as 235ST are connected to terminal N of the battery is employed for reset purposes, and the pulling of push button STPB will open said contact b and release 235ST relay and any other start relays which are picked up. Contact b of push button STPB is thus employed in lieu of the reset button shown on the upper right hand side of drawing D-2547, sheet 14A in aforesaid Manual No. 514. It should be pointed out that said contact b is also shown connected to terminal 17A of the office line coding unit, in a similar manner that the reset button in said drawing is connected.

The operator by depressing push button STPB completes the storages for field location 35, eld station 2.35, and the control panel is now available to select another location and establish control storages for that location.

It will first be assumed that at the time the operator depresses the start push button STPB, another field station is transmitting indications to the control oice over the code control communication system and, therefore, the controls for field location 35 cannot, as previously explained, be transmitted to said location; and that while the said controls are stored by the indication relays, as described above, the operator selects field location 36 to establish control storages to be transmitted to that location.

To select field location 36 the operator need only depress location selection push button 6PB on the control panel as push button BDP'B remains depressed from the previous selection of field location 35. Each group of location selection push buttons on the control panel being interlocked as previously explained, the depressing of push button `6PB returns push button SFB, previously depressed in the selection of location 35, to its undepressed or normal position. Back contact d of push button SP'B (FIG. 2) is therefore opened, opening the pickup circuit for location selection relay SSLC and that relay releases. The pickup circuit for location selection relay 36LC is closed over back contact d of push button @PB and relay 36LC picks up.

The release of relay 35LC opens, at its front contact b (FIG. 3a) andits front contact d (FIG. 3b) the stick circuits for relays lRP and 2LP respectively, and these relays release. The release of relay 35LC also opens at its front contact f (FG. 3c) the stick circuit for relay STP and that relay releases. The control panel is now available for the operator to establish control storages for field location 36 in a similar manner that the described control storages for location 35 were established.

The release of relay SSLC transfers the stick circuits for relays 35-1NWK and 351RWK (FIG. 5) from the front point of contact h of relay 35LC to the back point of that relay and relays SS-INWK and SS-IR'WK remain picked up. Said contact h of relay 35LC being a make-before-break contact the opening of the stick circuits to said relays, when the contact is transferring from its front contact point to its back contact point, is prevented. Similarly, the release of relay 35LC transfers the stick circuit for relay 35-2LHK (FIG. 6) from the front point of make-before-break contact n of relay SSLC to the back point of said contact and relay SS-ZLHK remains picked up. The transfer of these stick circuits also, as is obvious, disconnects the respective relays from the contacts of the function control push button repeater relays, and thereby removes the relays from under the control of the control panel. VThe controls to be trans- Y mitted to field location 35 thus remain stored until the code controlcommunication system is available for transmitting the controls tosaid location.

It will now be assumed that at the time the operator depresses the start push button ST PB as described above, no controls are to be initiated and established for another field station and, therefore, the control panel remains as last described, that is, with push buttons SDPB and SPB 2li depressed. Relay 35LC, therefore, remains picked up at this time.

Relay MP shown in FIG. 4b, picks up, as previously pointed out, when the M or master relay in the office line coding unit of the Form 514 code control communication system picks up. The M relay is not shown in the drawings but it is sufficient for purposes of this description to state that the M relay picks up when a start relay such as ZSSST (FIG. 3c) picks up if the communication system is at rest, that is, available for the transmission of control information. Reference is again made to said Manual No.. 5l4 and sheet 14A of drawing D2547 therein for a description of the operation of the code control communica-- leases after the expiration of its slow release period. How

ever, before front contact b of relay STP opens, the previously described circuit, including front contact f of relay 35LC and the front point of contact b of relay MP, closes momentarily, and since terminal A111 is connected to the cancellation windings or coils UCC and DCC (FIG. 2), these windings become energized momentarily. Push buttons 3DPB and SPB are therefore 'actuated to their normal (undepressed) positions, opening the pickup circuit for relay SSLC which releases. The control panel is now in its normal condition and available for selecting another field location. The release of relay 35LC releases relays lRP and 2LP as described previously, and also opens aft its front contact f (FIG. 3c) the :cancellation circuit just described. Relays 3S-1NWK, 35-1RWK, SS-ZLHK and 23581" remain picked up as previously described, but the remainder of the apparatus is now in its normal condition.

During the course of the coding action of the code control communication system station call relay 2358 (FIG. 4d) is picked up in a manner described in said Manual No. 514. Make-before-break contact c of relay 2355 (FIG. 3c) transfers the stick circuit for relay 235ST from the back contact point of relay 2355 to its front contact point and terminal 8A of the office line coding unit. Relay, ZSSST is maintained picked up by the circuit from terminal SA until the station selection portion of the communication code is terminated (8th step of the coding ac.- tion as described in said Manual No. 514), and the inte-rnal circuit in the otce line coding unit to terminal 8A is interrupted releasing relay ZSSST which is thus returned -to its normal position.

When station call relay 235s is picked up, yas set forth above, circuits are completed over front contacts d and e (FIG. 4a) of relay 2358 to transmit the stored switch and signal controls to field location 35 during the coding action of the code control communication system. The previously described reverse switch control communication circuit includes front contact d of relay 2358, the front point of contact c of relay 35-1RWK, front contact b of relay 35-1NWK and terminal 3A of the office line coding unit. The previously described control communication circuit for clearing signal 3S-2LB includes front contact e of relay 2358, the front point of contact g of relay 35-2LHK, back contact g of relay SS-ZRHK and terminal 5A of the ofiice line coding unit. The similarity between these circuits and the circuits to terminals 3A and 5A shown on rthe upper right hand portion of aforesaid drawing D-2547, sheet 14A, is readily apparent. The der sired controls are thus transmitted to field location 35, and relays SS-lNRWSR and 352LHSR (FIG. 4a) are controlled to Itheir reverse positions. The similarity between these relays and relays NRWSR and LHSR shown .in the lower right-hand portion of aforesaid drawing D-2547, sheet 15A, is also readily apparent. Station call relay 2358 is released at the end of the communication control code (16th step in said Form 514 code control communication system) and the above described circuits 25 to terminals 3A and 5A of the office line coding unit are opened.

The stored controls having thus been' transmitted to field location 35 it is yassumed that a control is established at that `location for controlling switch 35-1W to its reverse position and the .switch commences said movement or is now in transit. It is also assumed, that after the switch has occupied its reverse position signal 35-2LB clears for the desired train movement. The circuits at location 35 for accomplishing these function-s are not shown as they form no part of my present invention, but reference can be made to the aforesaid United States Patent 2,698,425, FIGS. 2d and 2e, and description thereof, for an understanding of the operation of the apparatuscontrolled by contacts of relays 1WS and ZLHS which are respectively similar to relays 35-1NRWSR and 35-2LHSR shown in FIG. 4a of my present drawings.

When a control is established and during the period that switch 35-1W is in transit, as 4assumed above, relays 35-1NWCR and 35-1RWCR (FIG. 5) are both released and the previously mentioned switch indication circuits to terminals 1 and 3 of the field line coding unit are closed. The circuit to terminal 1 includes the back point of con.- taet a of relay 35-1NWCR, back contact a of relay 35- RWCR, and contact a of relay 35-1NRWSR in its re? verse position. The circuit to terminal 3 includes the back point of contact b of relay 35-1RWCR, back contact b o relay 35-1NWCR and contact a .of relay 35- lNRWSR in its reverse position.. The energized condition of terminals 1 and 3 is transmittedto the control ofce by the code communicationsystem and is reflected at the control otiice by the energized condition of `both terminals 9A and 11A of the office line coding unit.

Delivery relay 235D (FIG. 4c) is momentarily picked up by the indication code being received in the control oice from field location 35 (16th step of indication code as described in Manual No. 514), and the previously described circuits from terminals 9A and 11A (FIG. 5)

are completed over the front points of contacts a and b f respectively, of relay 235D to relays 35-1NWK and 35-1RWK, respectively. The stick circuits for relays 35-1NWK and 35-1RWK are opened at this timeat the back points of contacts a and b respectively of relay 235D, but the indication pickup circuits for said relays being completed over the front points of said contacts, relays 35-1NWK and 35-1RWK, which it will be remem bered were both picked up to establish the switch reverse control code, remain picked up. The make-before-break contacts a and b of relay 235D insure that the circuits over the front-points of the contacts are closed before the stick circuits over the back points of the contacts are opened. Relay 235D subsequently `releases reestablishing the stick circuits for both relays 35-1NWK and 35-1RWK which thus continue to remain picked up. The indication lamp 35-1WRKE in FIGS. la and 1b continues to flash, giving the switch-in transit indication.

When switch 35-1W at eld location 35 has completed its movement to its full reverse position, relay 35-1RWCR (FIG. 5) picks up closing the front point of its contact b and opening its back contact a. The switch indication circuit to terminal 1 of the field line coding unit at location 35 is, therefore, now open at back contact a of relay 3S-1RWCR, and the indi-cation circuit to terminal 3 of said unit is transferred from the back point of contact b of relay 35-1RWCR to the `front point of said contact. The deenergized and energized condition of terminals 1 and 3 respectively, is now transmitted to the control office by .the code communication system and is reflected at the control ofce by the deenergized and energized condition of terminals 9A and 11A, respectively, of the olce `line coding unit. When delivery relay 235D is now momentarily picked up, relay 35-1RWK remainsk picked up as before but relay 35-1NWK is released as terminal 9A is deenergized. Relay 235D subsequently releases, relay SSJ-IRWK remains picked up, and relay 35-1NWK 26 remains released as its stick circuit is open at its own front contacta.

The release of relay 35-1NWK transfers the energizing circuit for the ilament of indication lamp 35-1WRKE (FIG. 1b) from the coded battery at the front point of contact g of relay 35-1NWK to terminal B of the battery at the back point of said contact and the lamp is steadily illuminated to indicate that switch 35-1Wv is occupying its reverse position. It will be remembered that it was previously stated that the track diagram is normally dark. However, from the circuit just described it is apparent that a reverse switch indication lamp remains steadily illuminated as long as its respective switch remains in its reverse position. This condition is not considered as a normal condition and the said lamp is maintained illuminated as a reminder to theoperator of the position of the switch. No other change in the indication lamp circuits takes place at this time.

As previously stated, relay 35-2LHSR (FIG. 4a) i controlled to its reverse position when the described stored controls are transmitted to iield loca-tion 35. Themovement of the contacts of relay 35-2LHSR to their reverse position deenergizes relay 35-2LASR (FIG. 6). This control circuit for relay SS-ZLASR is not shown in the drawings but, this relay is controlled by a contact of relay 35-2LHSR in a manner similar to the control of .relay LSSALS by contact 20 of relay L58HS in the previously mentioned Patent 2,580,150 to Earl M. Allen. Relay SS-ZLASH is accordingly released. The control of relay 35-2LHSR to its reverse position closes a circuit for supplying energy to terminal 5 of the `field line coding unit (FIG. 6). This circuit may be traced from terminal B of the battery over the reverse contact point of contact a of relay' SS-ZLHSR to terminal 5 of said coding unit. The purposes of this circuit will become apparent in. the description to follow.

The control of relay SS-ZLHSR to its reverse position and subsequent releasing of rel-ay 35-2LASR completesl a circuit for controlling 35-2LB to its clear condition, This circuit is not shown in the drawing but such signal control circuits are well known in the art-and the circuit may, for example, be similar to the control circuit for signal L58 shown in said FIG. 1b of the above-mentionedY Allen patent. The clearing of signal 35-2LB deenergizes relay 35-2LRGPR (FIG. 6) in a manner similar to the deenergization of rel-ay LSSRP in FIG. 1b of the Allen patent when signal L58, shown in said FIG.. 1b, clears.

Relay SS-ZLRGPR accordingly releases and energy is also supplied to terminal 7 (FIG. 6) of the ield line coding unit over a circuit extending'from terminal B of the battery over back contact a of relay SS-ZLRGPR tosaid terminal 7. The release of relay SST-ZLRGPR also initiates a code start for transmission of a signal clear indication code from field location 35 to the control oiice. (Reference is made to the upper right-hand .portion of drawing D-2547, sheet 15A, in aforesaid Manual No. 514, for an example yof the code starting circuits located at a eld location and to the description in said Manual for an understanding of the oper-ation of these circuits).

The code control communication system transmits an indication code and the energized condition of terminals 5 and 7 on the eld line coding unit is reflected by the energized condition of terminals 13A and 15A on the ofiice line coding unit. Relay 235D at the control oiiice again momentarily picks up to ydeliver' the indication to the proper relays. Relay 35-2LHK (FIG. 6) which it will be remembered was previouslyl picked up for the transmission of the control for clearing signal 35-2LB, remains picked up when relay 235D picks up yas it is then energized over its previously described indication pickup circuit including the front point of contact c of relay 235D and the back point of contact e of-relay 35-2RHK. Contact c of relay 235D is a make-before-break contact to insure the continued energization of relay 35-2LH-Kl 

